Composition for checking the functioning of fire detection installations and application to various types of detectors

ABSTRACT

Compositions for checking the functioning of fire detectors comprising at least 75% of at least one haloalkane, up to 15% of at least one volatile organic compound selected from the group consisting of alcohols, oxoderivatives, and ethers, a small amount of an organic compound having a vapor pressure less than 0.1 millibar, and an optional propellant. The composition can be used to check the functioning of ionization detectors, combustible gas detectors, and optical smoke detectors.

FIELD OF THE INVENTION

This invention relates to compositions for checking the functioning of fire detectors.

BACKGROUND OF THE INVENTION

Smoke, heat and combustible gas detectors are of several types that are generally very different in operation.

Ionization smoke detectors, whose functioning is related to the changes of the electric conductivity of the air in the presence of fire aerosols, react under the effect of combustion products in the form of visible or invisible fire aerosols.

According to the operating principle of these detectors, an electric field is set up between two electrodes by a DC voltage. When the air between the electrodes is ionized, for example by a radioactive source, the resulting ions move under the effect of the field in the direction of the oppositely charged electrode. An electric current results whose current strength depends on the number and velocity of the ions. When fire aerosols penetrate into the space between the two electrodes, a part of the ions is deposited onto the particles of these aerosols, up to about a thousand times heavier than the ions. The heavy ions thus obtained hardly move any longer because of the mass inertia and thereby no longer contribute to carrying of charges, and the current diminishes.

Combustible gas detectors consist of a semiconductive gas sensor selectively sensitive to certain combustible gases such as methane, propane and hydrogen.

In optical smoke detectors, the very sensitive optoelectronic system, being made up of a specially developed semiconductive diode as an infrared light source, a silicon cell as light receiver, a light absorber and a protection from light from other sources, functions according to the light diffusion principle. The optics of the diode emits light impulses in the shape of a hollow cone. As long as the measuring chamber does not contain any smoke, the infrared light does reach the receiver placed in the center of the axis of the light cone. In penetrating the labyrinth chamber, the smoke particles disperse the light rays in all directions. A part of the dispersed light reaches the photoelectric receiver which then produces an electric signal.

There is now no satisfactory product for checking the functioning of these three types of detectors.

Mixtures of dichlorodifluoromethane and diclorotetrafluoroethane in proportions of 80 and 20% by weight, respectively, offered in aerosol cans are now packaged to check the functioning of ionization smoke detectors. These mixtures are not suitable for other types of detectors.

There is now no satisfactory product for checking the functioning of all three types of detectors. The nature of the products to check the correct functioning of each type of detector is different, depending on the type of detector used.

For ionization smoke detectors, products are used that stop the ions created in the air by the radioactive source, particularly by the formation of sufficiently heavy particles, and of sensing radioactive source radiations. These products can be organic chlorofluoro, fluoro products and gases such as nitric oxide and carbon dioxide.

The combustible gas detectors respond selectively, depending on the nature of the hydrocarbon; on the other hand, they are all more sensitive to other products such as alcohols, ethers, aldehydes, ketones, and, generally, to numerous volatile organic compounds.

Two means can be used for optical smoke detectors to create particles diffracting the light. According to one method, an aerosol of fine liquid droplets, of products with a slight vapor tension less than 0.1 millibar, and preferably less than 0.01 millibar, dissolved in a large amount of a solvent with a high vapor tension, can be used. According to another technique, a liquid which, on vaporizing, sufficiently cools the atmosphere of the chamber to transform the steam of the air into ice crystals, can be used.

SUMMARY OF THE INVENTION

Effective compositions have been found to check the functioning of various types of smoke and combustible gas detectors. These compositions, in the form of homogeneous mixtures of products that are active in regard to the three main types of detectors now used, offer the advantage of being more all-purpose than existing mixtures which are active only toward a single type of detector.

The active products are introduced into the checking composition in such proportions that, regardless of the type of detector, there is a slight consumption of the composition of the mixture at each test, of 0.5 to 2 grams, corresponding to injection times of 1 to 2 seconds; a very slight response time of the detectors, maximum 10 seconds; and a very short persistence, less than 10 seconds. The persistence time is the period during which the detector remains on alarm after injection.

The mixture of active products further meets the following requirements: there is no danger of toxicity or corrosion, no formation of solid residues, with very slight vapor tension which would clog the detectors. Further, packaging in aerosol cans is easy and this mixture meets aerosol standards, and is not subject to a particular labeling requirement relating to toxic and flammable mixtures.

The mixtures developed in aerosol form to check the functioning of all types of smoke, optical or ionization and combustible gas detectors comprise at least one haloalkane in an amount greater 75% by weight, at least one volatile organic compound with simple oxygen function of the alcohol, oxo derivation, ether oxide type in an amount less than 15% by weight, and a small amount of organic product with a low vapor pressure, less than 0,1 millibar at most a few precent by weight.

In case all the preceding constituents are liquids, there is introduced into the mixture a propellant gas that is very soluble in these liquids, such as nitric oxide or carbon dioxide.

The haloalkanes can be selected from chlorofluoro, chloro or fluoro alkanes, such as trichlorotrifluoroethane. Each mixture can contain one or more haloalkanes.

Of the volatile organic compounds, the preferred compounds are compounds with simple oxygen function such as alcohols, particularly acyclic alcohols, oxo derivatives, and ether oxides. Of the ethers, ethyl ether has proven to be particularly advantageous. Also, alkyl phthalates are satisfactory. As organic products with low vapor pressure, there can be cited ethyl phthalate and butyl phthalate.

Mixtures containing 80 to 95% by weight of trichlorotrifluoroethane, about 1 to 10% ethyl ether and between 0.05 and 1% by weight of alkyl phthalate and the quantity sufficient for 100% by nitric oxide have proven to be very satisfactory checking products in the detection of fires. In particular, compositions containing 90 to 95% by weight of trichlorotrifluoroethane, preferably between 92 and 92.5%, and about 1% ethyl ether, between 0.05 and 0.10% ethyl phthalate or butyl phthalate and quantity sufficient, to 100% of nitrous acid.

DETAILED DESCRIPTION OF THE INVENTION

Examples that illustrate the invention in a nonlimiting way are given below.

EXAMPLE 1

    ______________________________________                                         Composition expressed in percentage by weight                                  ______________________________________                                         Trichlorotrifluoroethane                                                                           82.3 g                                                     Ethyl phthalate     1 g                                                        Ethyl ether         10 g                                                       Nitrous oxide       6.7 g                                                                          100 g   = 75.6 ml                                          ______________________________________                                    

The density of the mixture is 1.32.

Packaging parameters:

    ______________________________________                                         filling level        75.6%                                                     nitrous oxide pressure                                                                               8.2 bars at 20° C.                                                     11.7 bars at 50° C.                                total weight of product                                                                             100 g                                                     ______________________________________                                    

Characteristics: flammability : 10% of product with ignition point less than 100° C.; flammability of dispersion, zero; toxicity, zero. Actually, there are maximum admissible concentrations for exposures of 8 hours per day for 5 days per week without detectable effect for the individual.

    ______________________________________                                         Substance           ppm    mg/m.sup.3                                          ______________________________________                                         Trichlorotrifluoroethane                                                                           --     --                                                  Ethyl phthalate     --       5                                                 Ethyl ether         400    1200                                                Nitrous oxide       --     --                                                  ______________________________________                                    

EXAMPLE 2

    ______________________________________                                         Composition % by weight                                                        ______________________________________                                         Trichlorotrifluoroethane                                                                           83.3 g                                                     Ethyl phthalate     0.5 g                                                      Ethyl ether         10 g                                                       Nitrous oxide       6.2 g                                                                          100 g   = 75.2 ml                                          density 1.33                                                                   ______________________________________                                    

Packaging parameters:

    ______________________________________                                         filling level        75.2%                                                     nitrous oxide pressure                                                                               8.1 bars at 20° C.                                                     11.5 bars at 50° C.                                total weight of product                                                                             100 g                                                     ______________________________________                                    

Characteristics: flammability : 10% of product with ignition point less than 100° C.; flammability of dispersion, zero; toxicity, zero.

There are maximum admissible concentrations for exposures of 8 hours per day for 5 days per week without detectable effect for the individual of:

    ______________________________________                                         Substance           ppm    mg/m.sup.3                                          ______________________________________                                         Trichlorotrifluorotrifluorethane                                                                   --     --                                                  Ethyl phthalate     --     --                                                  Ethyl ether         400    1200                                                Nitrous oxide       --     --                                                  ______________________________________                                    

The mixtures were tested in one-piece aluminum aerosol cans with a volume of 405 ml, diameter 66 mm, height 143 mm, working pressure at 50° C.: 12 bars, equipped with a "Lindal 1" R10 or RT10 type valve with a standard plunger tube, with a hollow-cone direct vertical "Lindal" diffuser making possible a product delivery of 1 gram per second.

EXAMPLE 3

    ______________________________________                                         Composition % by weight                                                        ______________________________________                                         Trichlorotrifluoroethane                                                                               92.20                                                  Ethyl phthalate         0.10                                                   Ethyl ether             1.00                                                   Nitrous oxide           6.70                                                   density of the product 1.56                                                    density of more propellant product 1.51                                        ______________________________________                                    

Packaging parameters:

The mixture was tested in aluminum aerosol cans with a volume of 350 ml, diameter 65 mm, height 130 mm. Full cone: angle 25 to 30° C., impact pact of spraying from about 5 cm to 10 cm from the nozzle.

    ______________________________________                                         filling level       75%                                                        nitrous oxide pressure                                                                              7 2 bars at 20° C.                                                     12 bars at 50° C.                                   ______________________________________                                    

Characteristics: flammability : 10% of product with ignition point less than 100° C.; flammability of dispersion, zero; toxicity, zero, fog/smoke appearance, wetting at 10 cm, nonwetting at 20 cm.

EXAMPLE 4

    ______________________________________                                         Composition % by weight                                                        ______________________________________                                         Trichlorotrifluoroethane                                                                          92.25                                                       Ethyl phthalate    0.05                                                        Ethyl ether        1.00                                                        Nitrous oxide      6.70                                                                           100 g                                                       ______________________________________                                    

Characteristics: flammability : 10% of product with ignition point less than 100° C.; flammability of dispersion, zero; toxicity, zero, fog/smoke appearance, wetting at 10 cm, nonwetting at 15 cm. 

That is claimed is:
 1. A composition for checking the functioning of fire detection installations comprising trifluorotrichloroethane, nitrous oxide, ethyl ether, and an alkyl phthalate selected from the group consisting of ethyl phthalate and butyl phthalate.
 2. The composition of claim 1 containing from about 80 to about 95% by weight of trichlorotrifluoroethane, from about 1 to about 10% by weight of ethyl ether, from about 0.05 to about 1% by weight of a compound selected from the group consisting of ethyl phthalate and butyl phthalate, and nitrous oxide in a quantity sufficient to make 100% by weight.
 3. An aerosol composition according to claim 1 including a suitable propellant gas.
 4. A method of checking the functioning of fire detection installations selected from the group consisting of ionization detectors, combustible gas detectors, and optical smoke detectors, comprising introducing into the vicinity of the detector a small amount of the composition of claim
 1. 5. The composition of claim 1 wherein the constituents are all liquid, including a propellant gas soluble in the liquid.
 6. The composition of claim 5 wherein the propellant gas is selected from the group consisting of nitrous oxide and carbon dioxide.
 7. The composition of claim 1 containing from about 90 to 95% by weight of trichlorotrifluoroethane, about 1% by weight of ethyl ether, from about 0.05 to about 0.10% of a compound selected from the group consisting of ethylphthalate and butyl phthalate, and nitrous oxide in a quantity sufficient to make 100% by weight.
 8. The composition of claim 7 containing from about 92 to about 92.5% by weight trichlorotrifluoroethane, about 1% by weight of ethyl ether, from about 0.05 to about 0.10% by weight of a compound selected from the group consisting of ethyl phthalate and butyl phthalate, and nitrous oxide in a quantity sufficient to make 100% by weight.
 9. The composition of claim 8 containing about 92.20% by weight of trichlorotrifluoroethane about 1% by weight of ethyl ether, about 0.10% by weight of ethyl phthalate, and nitrous oxide in a quantity sufficient to make 100%.
 10. The composition of claim 8 containing about 92.25% by weight of trichlorotrifluoroethane, about 1% by weight of ethyl ether, about 0.05% by weight of butyl phthalate, and nitrous oxide in a quantity sufficient to make 100%. 